Water is a resource that is necessary for the daily existence of living things. A supply of water is generally provided to every building, whether it be a residential home in the city or country, an office building, or other habitat where people either.live or work. Water is usually stored in a reservoir, such as a tower, lake, river, etc., and then purified and coupled under pressure through a pipe network to the buildings. The pipe network can be a large main from which smaller laterals are routed to the individual buildings. With such a network, fresh water is constantly available to every person by simply turning on a faucet, or the like.
The storage of water in a reservoir and the purification of the same comes at a cost to the consumer. In contrast, rain water is available in many regions of the world and when collected from a rooftop and stored in an auxiliary tank, or other container near the building, can be used in a very cost effective manner. Indeed, rain water can be used in many homes as an auxiliary source of water. Thus, when the auxiliary supply of rain water is available, it can be switched to the plumbing system of the home for consumption, and when exhausted, the supply of water via the mains can be switched into operation to provide a continual supply of water.
A valve is employed to enable pressurised water to be supplied from the auxiliary tank to the plumbing system when such supply is available, but permits the use of the mains water when the auxiliary tank water is depleted and ceases to be available. The switching between the auxiliary water tank and the mains water should be automatic and should be achieved while maintaining separation between the two water sources.
Most water pumping systems that pump water from a tank sense the pressure in the downstream side of the pump and turn the pump on when the pressure drops below a threshold pressure, or below a certain water flow rate. In this type of water pumping system, unless a large accumulator is used for the intermediate storage of water, the pump turns on and off frequently. This operation loads the pump and is noisy.
It can be seen that a need exists for a water supply system where the pump is only turned on when a significant flow level in the water demand is reached, and when there is sufficient water in the auxiliary water tank. This feature minimises pump cycling and economises the cost of the water, as the less costly water in the auxiliary tank is used first, and when depleted, the more costly mains water is used.